“But we wanted to investigate why that is — which compounds are involved and how they may impact age-related cognitive decline.” ]

Early on, the theories were caffeine might be what helped protect the brain. But when they compared dark roast and a decaffeinated dark roast from the same kind of bean they noticed the caffeine wasn’t what was helping to protect the brain…

“The caffeinated and decaffeinated dark roast both had identical potencies in our initial experimental tests. So we observed early on that its protective effect could not be due to caffeine,” says Dr. Ross Mancini, one of the study’s coauthors.

That’s when they compared a light roast and a dark roast of the same varietal.

Comparing the two they realized certain compounds in coffee were released as coffee was roasted. It appeared the longer coffee was roasted the more profound the protective benefits of these compounds became.

“It is the phenylindanes, rather than any other coffee-related compounds, that seem to inhibit the amalgamation of tau and beta-amyloid. These are toxic proteins, of which the excessive buildup in the brain is a key factor in neurodegenerative conditions such as Alzheimer’s and Parkinson’s disease.

…

It appears that a longer roasting time causes the coffee beans to produce more phenylindanes. This suggests that dark roasted coffee — whether regular or decaf — has the strongest protective effect on the brain.”

Dr. Mancini observed this was the first time roasting of coffee beans and brain protection (specifically for Parkinson’s and Alzheimer’s had ever been observed. And this led her team to conclude if you wanted to get the most brain protection out of your coffee it would be best to drink a darker roast over a lighter roast.